The invention relates to a probe pin for electronic testing of semi-conductor elements, comprising an electrically conductive core element, whereby the core element is made up of a metallic alloy, and an electrically insulating jacket element, whereby the jacket element surrounds the core element over regions thereof and the core element comprises a distal contact section for electrical contacting to the semi-conductor element. Moreover, the invention relates to a method for producing a probe pin.
During chip production, semi-conductor elements are contacted with probe pins right after processing in order to test the functioning of the integrated circuits (IC) in un-sawn condition of the semi-conductor elements. The probe pins are fixed in a probe card that is matched to the design of the semi-conductor element. During the testing process, the semi-conductor element is pressed onto the pins and a contacting of the needles and the pads of ICs, possibly through a passivation layer, is established. Then, various parameters are tested, such as the contacting, the pass behavior at high current density, and the electrical behavior upon changes of temperature.
The probe pins must comprise high electrical conductivity and thermal conductivity, have good corrosion resistance, and also have high hardness as well as good elastic properties. With many materials, an increase in the hardness is often associated with an increase in brittleness, which is disadvantageous for the elastic properties and in terms of the processing properties.
Due to the latest development towards increasing miniaturization of ICs on the semi-conductor elements, ever more densely packed arrangements of probe pins on the probe card need to be implemented. Accordingly, there is a need for the probe pins to be increasingly thinner. In order to meet these requirements, the materials used to manufacture the probe pins need to comprise high hardness and good elastic properties and it must be possible to process them into thin wires.
Tungsten-based probe pins are known for testing on aluminum pads. Tungsten and tungsten alloys and tungsten ceramics are very hard, and are therefore well-suited for contacting of aluminum pads, since the oxide or passivation layer, which is omnipresent with aluminum pads, needs to be punctured first. Tungsten is sensitive to oxidation, though. The tungsten oxides thus formed adhere to the aluminum pads and thus lead to undesired contamination at the sites of contacting.
Tungsten is less well-suited for testing on gold pads since gold pads are not as robust as aluminum pads and often do not withstand testing with tungsten-containing probe pins for mechanical reasons.
For use on gold pads, Pd alloys are known, such as, for example, Paliney® H3C made by Deringer Ney or NewTec® made by Advanced Probing. Palladium is disadvantageous in that extensive reforming processes and precipitation hardening processes are required for the manufacture of suitable palladium alloys. This increases the number of requisite production steps. Moreover, the electrical conductivity of palladium just barely meets the requirements.
US 2006/0197542 A1 and US 2010/0239453 A1 disclose alloys based on iridium for use as probe pins. Iridium has a lower thermal and electrical conductivity than other platinum group metals, and is brittle and inelastic and thus difficult to process.